Rotatable airfoil kite



March 21, 1950 J. c. DONALDSON ROTATABLE AIR-FOIL KITE 3 Sheets$heet 1 Filed April 6, 19 8 U082 oz.

V INVENTOR. JESSE C. DONALDSON March 21, 1950 J. c. DONALDSON 2,501,442

ROTATABLE AIR-FOIL KITE Filed April 6, 1948 :s Sheet-Sheet 2 INVENTOR. JESSE C. DONALDSON A T TORNEKY.

March 21, 1950 J. c. DONALDSON 2,501,442

ROTATABLE AIR-FOIL KITE Filed April 6, 1948 3 Sheets-Sheet 3 INVENTOR: JESSE C. DONALDSON wuzw A TTOPNE VS.

Patented Mar. 21, 1950 UNITED STATES PATENT; OFFICE ROTATABLE mason. YKITE Jesse C. Donaldson, Long Beach, Calif, Application April 6, 1948, Serial No. 19,312

13 Claims. ,(01. 244-453) g This invention relates to aero-dynamics and more especially to an air-foil structure mounted for rotation about a longitudinal axis as a result of air flow across or at an angle to such axis.

The present invention is a structure that was conceived and developed as a result of extensive study and experiment with rotating elements having substantial length with respect to a crosssection which is generally wider than its thickness, the structure being mounted or having means for rotation about the central longitudinal geometric axis of the section, the structure being rotatable in a wind or other air current moving generally across the axis and, for best performance, at substantially right angles to the axis. A structure of the type just mentioned, if of a regular cross-section such as a flat plate, will freely revolve in either direction and as a result of the rotation a transverse force relative to the wind direction is obtainable, this force being in the general direction of movement of the leading portion of the structure or the portion of first engagement with the wind. The increased transverse iorce or lift is believed to be due to them:- celeration and consequent reduction of atmospheric pressure of the air flow over the downwind side of the air-foil coupled with the impact displacement force acting upon the upwind or impinging side of the air foil, i. e., its lower edge.

It is therefore an object of the invention to provide an aero-dynamic structure comprising an air-foil suitably mounted for free rotation in an air current, the rotation being about a longitudinal axis of the air-foil and at an angle transverse to the axis of rotation.

Another object of the invention is to provide an aero-dynamic apparatus comprising an elongated air-foil which is rotatable about the longitudinal axis and having end plates which serve to stabilize the rotation both from an area-dynamic as well asa gyroscopic standpoint.

A further object of the invention is to provide a rotatable air-foil structure adapted for functioning in a plurality of environments whereby the energy of a moving air column is deflected in a direction substantially at right angles to the air movement and which may be incorporated in a lift device such as aircraft, kites, windmills, water craft and land vehicles and for other purposes.

Another object of the invention is to provide a new and improved kite construction.

Another'object of this invention is to provide a new and improved kite capable of being controlled in its flight from the ground and having 2 new and improved control therewith.

Another object of the invention is to provide a kite of the desired character described having spaced dual control means extending at approximately right angles to the axis thereof andby manipulation of which the kite may be made to dive, dip, loop and perform other aerial maneuvers.

Another object of the invention is to provide a new and improved rotatable air-foil or a kite or similar article of high efficiency.

means associated Another object of the invention is the provision.

of a new and improved disc construction associated with a kite or air-foil of the intended character.

Yet another object of the invention is to provide in a kite or similar article new and improved, yet simple, bearing means.

Still another object of the invention is to provide a new and improved kite construction suitable for use and sale as a toy whose parts may be sold in disassembled or assembled relationship and which,when sold in disassembled form, may be readily assembled and constructed from its parts by. a child or the like,

This invention also has within its objects the provision of a new and improved maneuverable rotatable air foil kite of improved proportions and weight which is attractive in appearance and which may be readily and economically produced from available materials.

It is moreover among the objects of this invention to provide improvements in construction and performance over prior art devices intended to accomplish a generally analogous purpose.

With these and other objects in View, the invention consists in the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings. I

In the drawings:

Figure 1 is a perspective view of an assembled kite embodying this invention as flown.

Figure 2 is a plan view of the kite.

Figure 3 is an elevational view of thekite (as from the bottom of Figure 2 looking in the direction of thearrows in said figure), parts being cut away.

Figure l is an exploded view of the kite illustrating a mode of assembly and component parts.

Figure 5 is a fragmentary detail sectional view Figure 10 is a sectional view taken as on aline Hll0 of Figure 9.

Referring more particularly to the drawings;

and especially Figuresl through 6, there isillustrated a kite generally designated by the nu meral 2i! chosen as exemplifying one preferred embodiment of this invention. The kite has 4 plates 36 and 3?, this being adequate where the plates are spaced approximately 18 apart.

The ribs may be formed with circular openings 60 at their centers so that suitable bearings Bi provided on opposite ends of the kite may be positioned therein and thereby properly centered in the assembling of the kite.

The bearings 6 i which may be of wood, plastic, or other appropriate material, may be further provided with sleeves 62 in which the wires 30 and 3i may be loosely disposed for rotation. The

sleeves 62 may themselves rotate within the body of the bearings 6i or they may be press-fitted q therein. The ends 63 of said bearings, to prevent secured, respectively, to either. end 2! and 22.?

cords, threads, or the like 23 and 24. Said threads 23 and 2d are secured at one of their ends to a control stick 25 normally held in a horizontal position by the operator to sustain horizontal flight. The other ends of the threads 23 and Marc secured to the kite as by means of wires and 3! in a manner which will appear.

The kite 26 preferably comprises a central rotat'able wingor air foil section and end plates or discs 36 and 31. The discs may be at right angles to the axis of the air-foil section or-they may be in cambered relation thereto. As may most clearly be seen from Figures 3uthrough 6, the air-foil section 35 may be formed with a hollow interior 35. Also, it may be provided with arbitrarily designated reversible leading and trailing edges 38 and 39, respectively, and upper and lower sides 38 and M, respectively.

/ The air-foil is preferably formed with diametrically opposite convex surfaces 44 and 45 blending into concave surfaces 46 and 47, respectively, to form an appropriately shaped structure having good aero-dynamic qualities. The respective concave and convex portions of the sides 48 and ll merge at the edges 38 and 39.

Any suitable material may be employed for the air-foil section but it hasbeen found desirable to make the same of a chip board or tag board of an appropriate thickness which is preferably formed into the shape illustrated-and cemented as along a seam line 50.

In order to properly shape the air-foil section, corrugated forming ribs such, for example, as the rib 5| of Figures 3 through 6, may be disposed in opposite ends of the air-foil. Ears 52 and 53 upon the corresponding convex edges 54 and 55 of the rib section may be provided together with complementary notches 56 and 5'! in such a manner that in the assembled relationship of the parts, the notches 5B and 51 accommodate said ears 52 and 53 in order to assure a proper shaping of the air-foil section and the correct positioning of the air-foil with respect to the ribs. Said ears and corresponding notches may be positioned in any desired location and-may, of course, be substituted for any other marking or positioning indicia.

It has been found that in the commercial embodiment of the kite in question, while any other material can be substituted, the ribs 5! may be formed from corrugated card board, thereby providing a suitable rigidity and thickness without undue weight. Rib sections such as 5| may be provided at any spaced intervals along the airfoil but it has been found satisfactory to include only two at opposite ends corresponding to the their withdrawal from the body of the bearings 6i and likewise to avoid sticking of the bends and 66 of the wires 33 and 3i during relative rotation of these parts, may be flared.

The wires 3t and 3! may include a short end '58 and a relatively long arm 59 calculated to extend beyond the plates 38 and 3'! in the assembled form of the kite, as illustrated most clearly in Figures 2 and 3, and formed at its opposite ends with a loopl't into which the threads 23 and 24 may be respectively tied.

The plates or discs 3% and 3? may be of the shape of pie plates, cake plates, or the like, but as shown as formed of papier-mach or other lightweight material having strengthening annular channels and ridges i2 and i3 concentrically formed therein. Preferably also, the central portion is raised in the manner of a boss M with tapered sides adapted to conform to the correspondingly tapered edges is of the bearings El. In the construction of the preferred form of kite illustrated in Figures 1 through 6, above discussed, it is, as has been suggested, possible or evendesirable to form the separate parts, to wit, the plates or discs 36 and 3? separately and to form the air-foil 35 in the shape of a cylinder which may be fiat for shipment or packaging and either pre-formed so far as its concave-convex contours are concerned or permitted to adapt itself to the shape of the ribs 5E after insertion of the latter into the ends of the air-foil by the ultimate purchaser. The ribs 5! may likewise be separately formed for convenient packaging, and the bearings 6 I, together with their optional brass sleeves 62 and wire 3% or 3!, may comprise assembly units separate from the balance of the structural parts.

If the above suggested mode of packaging is used, the parts may be in boxed form and assembled in the following manner by the ultimate consumer:

The air-foil section 35 may be expanded from a normal flattened position. (It is preferably pre-glued as along a seam line 56.) The ribs 5! may then be glued completely around their edges and inserted in the ends 8! of the air-foil with the ears 52 and 53 disposed, respectively, in the notches 56 and 5?. Thereupon, the wires may be extended through central openings 32 in the discs 3% and 3?, preferably with the raised ridge surfaces 12 and 13 outwardly and disposed on the same side as the loops l0.

Cement may then be applied to the tapered surfaces '16 of the bearings and to the corresponding inner surfaces of the bosses M. Thereafter, the bearings may be pressed into place as illustrated, for example, in Figures 3 and 5.

Following the uniting of the respective wires, bearings and plates, and the cementing of the ribs within the end of the air-foil, the three resulting parts may be united as by applying cethen be provided with threads 23 and 20 secured,

as illustrated most clearly in Figure 1, by one of their ends, within the loops of the wires 30 and 3| and by their other ends at opposite ends 90 and SI of the stick 25.

It is preferable, although not essential, that the threads 23 and 24 during the flight of the kite be substantially parallel and accordingly it has been determined that a kite of approximately 18" in length between the discs 36 and 3i may be operated by a stick 25 of approximately equal length. In any event, it is desirable that the stick 2 5 and the kite be of such length that when the kite is flown at any height, say approximately 300 feet, the threads 23 and 20 will retain their separated and untangled and uncrossed relationship.

In enjoyment of the use of the kite of this invention the operator may stand with his back to the wind in a conventional manner holding the kite before him on a horizontal axis substantially as illustrated, for example, in Figures 2 or 3. Initially, he may manually rotate the kite with respect to the oncoming wind, as illustrated by arrows in Figures 1 and 6 and as also indicated on the kite by arrows in Figure 2. Rotation will be in such a direction that the oncoming wind will blow over the kite in the same direction as the rotation of the topmost edge thereof. Thereby, the concave surfaces will, in effect, scoop the wind While the convex surface will provide an upward impact or thrust as the kite rotates.

During such rotation the movement of the upper edge of the kite in the same direction as the wind will also bring about a relative reduction of air pressure above the air-foil which will contribute to the lift. Various-shapes of air-foil may be utilized, from a substantially flat elongate plate of negligible thickness to one of a thickness approximately equal to its breadth. Thus, an air-foil may have a width, as illustrated, for example, in Figure 2, from the edge 38 to the edge 39 approximately equal to, or slightly in exoess of, twice the thickness (Figure 3) from the side 40 to the side 4|.

The control stick is ordinarily held level, with both strings 23 and 24 of the same length. By dipping one end of the stick ill or other appropriate manipulation (Figure 1), the kite may be caused to dip in one direction, or by lowering the end 00 of the stick the kite may be caused to dip in an opposite direction. Similarly moving the end 90, for example, towards the kite will cause the kite to maneuver in an opposite direce tion from that occasioned by moving said end 0! theretoward (as indicated by dotted arrows in Figure 1), etc. By appropriate manipulation of the stick, therefore, the kite may be caused to slip to either side, dive, loop, fall, rise, etc. When the operator has achieved a desired degree of skill, it is possible to put the kite through any number and variety of movements.

The modified form of kite illustrated in Figures 7 and 8 and air-foil I00 may comprise an elongate portion having opposed convex surfaces IOI and I02 and opposite concave surfaces I03 and I04. The ant-foil section I00 may be secured to side plates I05 as by means of bentover ears or tabs I06 glued to the corresponding faces ofthe discs I05 or by any other suitable means. I

The discs I05 may be formed with ridges-I08 and I09 in a similar manner to the first preferred embodiment above described and may likewise be provided with bearings I I0 cemented or otherwise secured to the corresponding central portion of the disc in a manner similar to that described for the embodiment of Figures 1 through 6'. A cut-out H2 may be formed in the air-foil adjacent the discs I05 in order to accommodate the end H3 of the wire H4 and the bearing H0.-

' The performance and mode of operation of the form of Figures 7 and 8 will be similar to that of Figures 1 through 6, there being in. the form-of Figures 7 and 8 preferable, though optional, corresponding plates I05 on either end of the airfoil I00.

In the embodiment of Figures 9 through 10 an air-foil MI is shown having opposite substantially trapezoidal, triangular or other shaped left and right halves 202 and 203. The cross-sectional appearance of the air-foil may be similar to the embodiment of Figures 1 through 6, or to the embodiment of Figures 7 and 8 but, as illustrated, corresponds with the second embodiment. A single peripheral flange or disc 205 having a turned reinforcing and stiffening edge 206 may be formed with a substantially S-shaped slot 201, through which the air-foil section 20I may be inserted and cemented in place during assembly, as illustrated in Figure 9, the cement being there designated by the numeral 208. Stabilized gyro like rotation is thereby achieved.

Appropriate plugs or bearings 2 lflmay be slot, ted at 2! l for insertion over and cementing to the respective edges 2l2 of the air-foilJ Such bearings may be formed with sleeves 2I3 extending to a recess within the bearings 2| 0 at which place the ends of the guide wires 2I5 may be peened in any known manner in order that they may turn freely.

Loops 2I8 may be formed in the ends of the wires 2| 5 for the accommodation of control threads as in the other illustrated embodiments of the invention. The shape of the air-foil 20I, while preferably tapered towards its outer end, may be given any shape, and may be round, rectangular, square, oval, or any combination of these.

The material of which the second and third embodiments is made Lmamin comparableportions, be similar to the material of which the first embodiment is made. Anyiof these may be formed of suitable light material such as alu-.

minimum, balsa wood, magnesium, paper, or the like, and the parts may be reinforced by strengthening members, ribs, struts, braces, and the like. For example, if a frame for the kite be made with balsa wood, a skin may be mad of silk, rice pa per, or other Well-known material in a manner well-known to those skilled the art of miniature aircraft construction.

The direction of rotation of the modified form of Figures 9 and 10 relative to the wind is illusof discs may be provided in any embodiment and it is equally obvious that the shape of any of the air-foils of the various illustrated forms of the invention, or others, may be interchanged with the disc or disc-construction of any selected embodiment.

The plates or discs in any of the illustrated embodiments serve an important purpose in stabilizing the rotation of the kite, such stabilizing effect acting to resist longitudinal shifting of the air-foil, and also providing a gyroscopio stability to the kite. The plates or discs may be formed with annular, peripheral ribs, bosses, flanges, and the like, of a weight calculated to provide as much inertia as proves feasible in the variant conditions under which the kite may be used.

This invention features the provision of a new and improved air-foil construction for kites and a new and improved relationship of the parts and their construction to provide a device which is adaptable for use not merely for kites but for air-foils in general and having associated therewith, particularly as intended for a kite, a. novel control mechanism comprising parallel cords intended to be operated either by a single control stick or device, as illustrated, or separately connected to or held by independently manipulative control members or by one or more operators. The construction is such that the kit may be economically produced and its parts replaced as necessary, thereby providing, in accordance with its primary purpose. a delightful, entertaining and instructive apparatus.

To illustrate the approximate dimensionsof a preferred model of the device, the diameter of a disc is found suitable in size at a diameter of nine inches when made of papier-mach. The corresponding air-foil may be approximately eighteen inches in length between the discs as in the form of Figures 1 through 6, for example. Said air-foil may also have an approximate width of four inches and an approximate thickness of two inches or less. The bearing members may be made of Wood, or light metal, and if of the latter, should be hollow to minimize their weight. The other parts may be in proportion as they are shown in the drawings.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent structures.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

' 1. A kite comprising a rotatable wing, journal means for fre rotation of said Wing about a central axis, and individually controllable force transmitting elements separately engaging said journal means, respectively.

2. A kite comprising an elongate rotatable wing, journal means for free rotation of said wing about its long central axis, and controllable force transmitting elements directly engaging said journal means, said elements comprisin at least one pair of lines extending substantially at right angles to said central axis in substantially parallel spaced relationship to one another and under the control of an operator.

3. A kite comprising an elongate rotatable wing, journal means for free rotation of said wing about its long central axis, and controllable force transmitting elements engaging said journal means, said elements comprising at least one pair of cords extending substantially at right angles to said central axis in substantially parallel spaced relationship, and an elongate control stick normally held parallel to said central axis, said cords being directly secured to respective ends of said control stick, and under the control of an operator.

4. A kite comprising an elongate rotatable wing, journal means at each end thereof for free rotation of said wing about its long central axis, a pair of individually controllabl force transmitting elements engaging said journal means at opposite ends of the kite respectively, and at least one disc-like member of approximately twice the diameter of the wing. extending radially from and encircling said wing.

5. A kite comprising an elongate rotatable wing, journal means for free rotation of said wing about its long central axis, individually controllable force transmitting elements secured to said journal means at longitudinally spaced points, and spaced disc-like members of at least twice the diameter of the wing extending radially from and encircling said wing.

6. A kite comprising a rotatable wing, journal means for free rotation of said wing about a central axis, controllable force transmitting elements engaging said journal means, said'wing comprising surfaces diametrically opposed with respect to said central axis, and a discof at least twice the diameter of the wing coaxially secured thereto.

7. A kite comprising a rotatable wing, journal means for free rotation of said wing about a central axis, and controllable force transmitting ele ments engaging said journal means, said wing comprising a hollow airfoil having opposed, substantially'S-shaped, self supporting walls defining relatively sharp meeting edges therebetween.

8. A kite comprising an elongate rotatable wing, journal means for free rotation of said wing about its long central axis, controllable force transmitting elements engaging said journal means, and spaced disc-like members extending,

radially from and encircling said wing, and having a recess formed at their centers, said journal means comprising a bearing body having a central passage therethrough, said body being adapted to nest in said recess, a sleeve in said body and an axle member designed to turn freely in said passage and extending beyond the ends of said wing, and individual direct control cords secured to each axle member.

9. A kite comprising an elongate rotatable wing, journal means for free rotation'of said wing about its long central axis, controllable force transmitting elements engaging said journal.

means, spaced disc-like members extending radially from and encircling said wing, and having a recess formed at their centers, said journal means comprising a bearing, body having a central passage therethrough, said body being adapt-.

ed to nest in said recess, a sleeve in said body and an axle member designed to turn freely in said passage and extending beyond the ends of said wing, and individual direct control cords secured to each axle member, said wing being notched at its ends to accommodate said bearing bodies.

10. A kite comprising an elongate rotatable wing, journal means for free rotation of said wing about its long central axis, controllable force transmitting elements engaging said journal means, spaced disc-like members extending radially from and encircling said wing, and hav-- ing a recess formed at their centers, said journal means comprising a bearing body having a central passage therethrough, said body being adapted to nest in said recess, a sleeve in said body and an axle member designed to turn freely in said passage and extending beyond the ends of said wing, and individual direct control cords secured to each axle member, said axle member comprising a wire having a bend therein forming a portion extending in and parallel to the central axis of the wing, and a portion offset from said axis for the affixation of said individual direct control cords.

11. A kite comprising an elongate rotatable wing, journal means for free rotation of said wing REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date l,825,4:93 Wander Sept. 29, 1931 2,107,808 Van Ittersum Feb. 8, 1938 2,338,478 Garber Nov. 6, 1945 FOREIGN PATENTS Number Country Date 483,043 Great Britain Apr. 7, 1938 121,698 Switzerland Aug. 1, 1927 146,887 Switzerland July 16, 1931 

